1. Field of the Invention
The present invention relates generally to appliances that may be hazardous if left unattended, and relates particularly to reducing hazards of appliances left unattended.
2. Description of the Prior Art
Appliances such as stoves may be hazardous if left unattended. Items which are on the stove may boil over or overheat when left unattended, leading to the production of smoke and fire. Throughout the years, a number of innovations have been developed relating to the reduction of hazards from unattended stoves, and the following U.S. patents are representative of some of those innovations: U.S. Pat. Nos. 4,070,670, 4,659,909, 4,775,913, 5,380,985, and 5,717,188. More specifically, U.S. Pat. No. 4,070,670 discloses a device that senses the occurrence of the hazardous conditions of water spillage or overflow in a cooking burner unit, sounds an alarm when a hazardous condition has occurred, and shuts off fuel flow to the burner. Although is it desirable to sense the occurrence of a hazardous condition, and it is desirable to sound an alarm when the hazardous condition has occurred, it would also be desirable to prevent a hazardous condition in the first place. In this respect, it would be desirable if an apparatus would alert a person that an appliance has been unattended for a predetermined period of time. Then, once alerted, the person could attend to the appliance and prevent the occurrence of a hazardous condition.
U.S. Pat. No. 4,659,909 discloses a device that shuts off electric power to a kitchen range when the hazardous condition of smoke has been detected. Here is another example of a device that responds to a hazardous condition rather than alerting a person prior to the occurrence of the hazardous condition. Another feature of this and the previously discussed patent relates shutting off power to the appliance one the hazardous condition has been detected. To cut off power to the appliance, the wiring or fuel source for the appliance is modified. Such modifications can be time consuming and costly. In order to avoid time consuming and costly modifications to the wiring or fuel source of an appliance, it would be desirable if a device were provided which simply signals a person to be attentive to an appliance without the need for modifying the wiring or fuel source of the appliance.
U.S. Pat. Nos. 4,775,913, 5,380,985, and 5,717,188 have a number of features in common. They all relate to an electric stove. They all sense the presence of a person near the electric stove. They all have a timer which begins to run when the person is not sensed in the presence of the electric stove. They all turn off electric power when the person has not been sensed near the electric stove for a predetermine period of time. In addition, they all do not employ an alarm to alert a person that the predetermined period time has expired. Rather than turning off an electric stove when a person has not been sensed for a predetermined period of time, it would be desirable if a person would be signalled audibly when the predetermined period of time has expired.
Still other features would be desirable in an appliance attendance monitoring apparatus. For example, in some instances, it would be desirable if both a person would be given an audible signal and electric power would be shut off to the appliance after a predetermined period of time has elapsed.
A large number of electric ranges are presently in use which do not provide alarms to signal a person that the electric range has not been attended to for a predetermined period of time. In this respect, it would be desirable if an appliance attendance monitoring apparatus were provided that can be easily retrofitted to such electric ranges.
Thus, while the foregoing body of prior art indicates it to be well known to use monitors for turning power off to an appliance after a predetermined period of time has expired without sensing the presence of a person, the prior art described above does not teach or suggest an appliance attendance monitoring apparatus which has the following combination of desirable features: (1) employs an audible signal to alert a person that an appliance has been unattended to prevent the occurrence of a hazardous condition; (2) signals a person to be attentive to an appliance without modifying the wiring or fuel source of the appliance; (3) signals a person audibly when a predetermined period of time has expired with an appliance not being attended to by a person; (4) both provides an audible signal to a person and shuts off electric power to the appliance after a predetermined period of time has elapsed without a person being in attendance of the appliance; and (5) can be easily retrofitted to electric ranges that do not currently provide alarms to signal a person that the electric range has not been attended to for a predetermined period of time. The foregoing desired characteristics are provided by the unique appliance attendance monitoring apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.